1. Technical Field
The present disclosure relates to the fabrication of micro-electrochemical devices.
2. Description of the Related Art
A micro-electrochemical sensor can be formed, in a substrate, as a microscopic structure that provides a platform for a chemical process or reaction. Some reactions cause electrical effects such as changes in voltage or current that can be sensed by electrodes attached to the microstructure. Thus, such a microstructure provides an electrical detector that can be used to monitor the chemical process. Common examples of micro-electrochemical sensors include biosensors such as, for example, immunosensors that can be used to analyze biological samples, as described in U.S. Patent Application Publication No. 2012/0034684 (hereinafter, “the '684 patent application”).
Semiconductor microstructures having dimensions in the range of about 1-10 microns can be manufactured for biotechnology applications using techniques, materials, and equipment similar to those that have been developed for the microelectronics industry. For reliability, it is important that microstructures that make up the platform are mechanically stable. In general, achieving a mechanically stable microstructure can be particularly challenging if, for example, the dimensions or the material properties of adjacent microstructural elements are very different from one another. For example, a multi-layer microscopic structure situated next to a macroscopic structure can be vulnerable to destructive events such as cracking, rupturing, peeling, or delamination of the layers. Such events can occur in response to development of a composite shear stress that results from imbalances in compressive and tensile stresses associated with the various layers of the microstructure. Structural instabilities that cause peeling or delamination of thin films on a silicon substrate are a recurring problem in the fabrication of electronic devices. Historically, this has been especially problematic near the boundaries of “trench isolation” areas formed in the silicon as electrical boundaries between neighboring transistors.